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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science, Ltd
    Freshwater biology 41 (1999), S. 0 
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Interactions between environmental variables and 0+ fish assemblages in the upper River Garonne (France) were quantified during late August 1995.2. The abundance and diversity of the fish assemblages in floodplain channels were modelled using Artificial Neural Network (ANN) analysis and nine variables: the abundance of the six dominant species, fish specific richness, overall abundance of 0+ fish and the Shannon index of diversity. Multiple regression analysis was also used to assess ANN performance.3. Using 596 samples, correlation coefficients (r adjusted) between observed and estimated values of the nine dependent parameters were all highly significant (P 〈 0.01). Expected values from the tested data were significantly related to the observed values. The correlation coefficient between observed and estimated values (r) varied from 0.70 to 0.85.4. The ANN provided a high quality prediction, despite the complex nature of the relationship between microhabitat composition and fish abundance.5. Garson’s algorithm was used to provide the explanatory power needed in ecology when using black-box models. Parameters contained in the models (i.e. weighting) were used to determine the relative contributions of explanatory variables and thus to ascertain the structure of fish communities.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 66 (2005), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Spatial patterns in the combinations of biological traits of fish communities were studied in the Garonne River system (57 000 km2, south-west France). Fish species assemblages were recorded at 554 sampling sites, and the biological traits of species were described using a fuzzy-coding method. A co-inertia analysis of species distributions and biological traits identified some spatial patterns of species trait combinations. Fish species richness progressively increased from up- to downstream sections, and the longitudinal patterns of fish assemblages partitioned the river into clear biogeographic areas, such as the brown trout Salmo trutta(headwater streams), the grayling Thymallus thymallus, the barbel Barbus barbus and the bream Abramis brama zones (most downstream sections), which fitted with Huet's well-known zonation for western European rivers. Only a few biological traits, chiefly related to life-history attributes, significantly influenced the observed fish distributions. Fecundity, potential size, maximum age and reproductive factor increased from headwater to plain reaches. As a theoretical framework for assessing and predicting the functional organization of stream fish communities, spatial variations in species traits can be related to habitat conditions, thus providing explicit spatial schemes that may be useful to the design of both scientific studies and river management.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 33 (1997), S. 277-285 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Riverine ecosystems are subject to a large variety of man-made influences, and in recent years a new public awareness of the need to protect rivers has emerged within the industrialized world. The present study focuses on the effect of abatement of pollution from one factory on the recovery of fish and macroinvertebrate species richness in the River Petite Baïse over a 20-year period (1973–1993). Until 1973, the Petite Baïse (75 km in length) received not only factory waste (nitrogenous rich effluents) but also the untreated sewage of many villages and agricultural runoff from the river's catchment. In 1970, macroinvertebrates and fishes were absent in the river despite having initially been classified as of the barbel Barbus barbus zone, and extensive efforts were made by the factory to reduce pollution to allow the riverine community to recover. Regular surveys between 1973 and 1993 revealed a progressive improvement in water quality and the recolonization of the river by macrobenthic and fish populations. Macrobenthic fauna species richness gradually increased from zero in 1970 to level 8 or 9 in 1993 (Verneaux and Tuffery method), reflecting improvements in river water quality. Fish were not observed until 40 km downstream of the factory in 1978, 16 km in 1980, and approximately 5 km by 1990. Fish species richness increased from five in 1978 (barbel, chub Leuciscus cephalus, stone loach Barbatula barbatula, minnow Phoxinus phoxinus, gudgeon Gobio gobio) to eight in 1990 (the carnivorous brown trout Salmo fario, the omnivorous chub, and six benthophagous fishes: gudgeon, barbel, minnow, stone loach, sofie Chondrostoma toxostoma, carp Cyprinus carpio). Fish biomass 45 km downstream the factory increased from 1 g/m2 in 1978 to more than 5 g/m2 by 1990. Recolonization of the river, in particular those areas furthest downstream from the factory, occurred as a result of reductions in the nitrogen inputs emanating from the factory.
    Type of Medium: Electronic Resource
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